(continued from Part 3. This concludes the article.)
Battery Safety
If you’ve ever watched the news you’ve probably heard stories about exploding Lithium batteries in cell phones, electronic cigarettes, USB battery packs, etc. They’re all true – lithium is an extremely hazardous chemical; it’s poisonous, it’s unstable, it burns extremely fast and hot (>3500F) and it produces hazardous gas when it burns. So why is it used in all of the most common forms of battery electrolytes? Because it has the best cost/size to energy density ratio currently available and manufacturers decided it’s worth the risks, and consumers agree with them.
The underlying cause of lithium batteries catching fire and exploding is thermal runaway, which is an uncontrollable, self-sustaining chain reaction triggered when heat generation within a battery cell exceeds its ability to dissipate heat. For most lithium batteries that starts at an internal temperature of around 175F, but it can be accelerated by mechanical damage, overcharging, external heat, shorting or manufacturing defects. Shorting out a lithium battery is a sure-fire way to get it to catch on fire, and puncturing the casing can cause it to explode.
Poor manufacturing quality is one of the leading causes of thermal runaway, with factors such as anode/cathode overhang gradually impacting the battery’s chemistry as it’s used. Consider the humble 18650 battery – over 5 billion are manufactured worldwide every year, and they’re used either individually or combined into multi-battery packs to power everything from flashlights to EVs. A company called Lumafield did a detailed CT scan study [1] of 18650 batteries and found that low-cost no-name 18650 batteries had seven times lower quality than name brand ones, which significantly increases the probability of the low-cost batteries catching fire. The lesson here should be to stick with well-know name brands when buying lithium-based batteries.
Extinguishing lithium battery fires is extremely difficult – they generate their own oxygen and extreme heat when they burn, and the entire battery is essentially a single large fuel source. Using water on lithium battery fires can actually cause more problems, since lithium may react violently with water, producing flammable hydrogen gas and additional heat which can worsen the fire or cause explosions. Most fire departments don’t even try to extinguish lithium fires – they simply let it burn itself out while trying to keep it from spreading. Recently new types of fire extinguishers have started to become available from companies such as Life Safe Technologies [2], Burn Buster [3], Zenova [4] and others, targeted specifically at lithium battery fires.
If you have lithium batteries you should be prepared to fight a lithium battery fire. I know that the fire department says you should immediately evacuate your house and wait for them to arrive, but in a disaster scenario there’s a good chance the fire department won’t be available, and I don’t plan on losing my entire house and all of my possessions due to one battery fire. I keep a lithium fire extinguisher and a fire mask [5] on the wall outside of my shop, which is where most of my batteries are stored and charged. You shouldn’t store the fire extinguisher in the same room as the batteries – if they start burning they’ll quickly release a large amount of toxic smoke, so you’ll need to evacuate that room in a hurry. I also keep another large standard fire extinguisher next to the door for more common things nearby that the battery fire might set ablaze.
Safely disposing of lithium batteries is a big challenge. Even an old lithium rechargeable battery near the end of its life can still cause a fire, so you want to make sure they’re disposed of in a safe manner. During ‘normal’ times, most towns have regular hazardous waste disposal days or facilities, but you still need to store them until you can safely dispose of them. I wrap them in duct tape to ensure the terminals are covered so they can’t short out, then place them in a small metal trash can and cover them with sand. The trash can is stored well away from my house in a cleared area in small covered and elevated box with a lid (elevated to keep it out of water and allow access in deep snow).
In a post-disaster scenario when there aren’t any safe disposal methods available my plan for disposing of old lithium batteries is to start a small fire away from everything in a clear area and toss the batteries into it to intentionally burn them up in a somewhat controlled manner. Note that even small lithium batteries can explode in a somewhat energetic manner, so make sure there’s nothing nearby that can catch on fire and be standing by with a fire extinguisher or bucket of sand to extinguish any stray flames.
Batteries should be stored safely, especially if you’re storing them long-term in out of the way places. The most critical point is that batteries should always be stored so their terminals are protected and can’t accidentally be touched and short-circuited, which can lead to fires. Most primary batteries come in blister packs with a thin plastic shell glued to a cardboard backing; the problem is that the glues wears out over time and the batteries can become loose, allowing them to move around and possibly short out. Some rechargeable batteries come in plastic cases, which work well for storing them. I purchased a bunch of different plastic cases [6] designed to hold different sizes of batteries and transfer any batteries that come in blister packs into the cases. The second storage recommendation is to store your battery cases in metal containers, such as galvanized steel trash cans. That way, if a battery does catch fire, the can will reduce the risk of the fire spreading rapidly.
My Approach
I own a lot of electronics, some with built-in batteries and some that use various types of removable ones, so over time I’ve developed an approach to battery management that works well for me. First, I’ve divided my batteries into four categories – primary batteries in long-term storage, rechargeables in active use, rechargeables in long-term storage, and lastly devices with built-in batteries.
Recharging quickly may not always be possible and rechargeable batteries in long-term storage should always be stored partially charged, so I wanted to have access to ‘full’ batteries quickly in an emergency. I store a bunch of primary (non-rechargeable) batteries for quick access to power. As I’ve mentioned previously Energize Ultimate Lithium primary batteries can be stored up to 25 years, so I purchase those in AA, AAA and 9V sizes whenever I can find them on sale. I write the earliest expiration date for any of the batteries stored in a case on the outside so I know when I should use them up or dispose of them, but honestly battery technology will probably change by the time they expire. I also store primary version of other batteries I need such as CR123A, CR2032, CR2025 and others.
Managing rechargeable batteries is a lot more complicated. As I mentioned earlier how you use, recharge and store rechargeable batteries can have a significant impact on their life, so I put a system in place that’s slightly complicated but works well for me. Since no two batteries are ever identical my approach probably isn’t the 100% perfect solution for every individual battery I have, but it’s a good compromise between battery health and my time investment. To start with, I put a small inventory number sticker [7] on every rechargeable battery and device with a built-in battery as soon as I received it; the stickers are small enough that they’ll even fit a AAA battery with no problem. The information for the battery/device is entered into my inventory management system that I described in a previous SurvivalBlog article [8] along with the acquisition date. I then set a reminder for the future date when they’re supposed to die. (Yes, I have reminders set 10 and 25 years out 8-)).
I manage rechargeable batteries in two ways – active use and long-term storage. Active use are batteries that I use on a regular ongoing basis, and I built a battery charging cabinet that I keep those in. There are several different chargers in the cabinet – I have a LiitoKala Lii-S12 for the most common AA/AAA/18650/9V/RCR123A batteries, a bunch of USB charging hubs for batteries that have built-in USB charging and some odds and ends chargers such as a DJI drone battery charger, two chargers for my Yaesu VX-6R batteries and others for various battery types. I also have several other chargers located around the house so there are batteries nearby when I need them.
Long-term storage of rechargeable batteries is a trickier proposition, since different chemistries behave in different ways when not used. First, most rechargeable batteries should never be stored either fully charged or empty – the rule of thumb is that Lithium or nickel-based rechargeables should be stored between 30% and 50% charged. This puts the least amount of strain on the battery and reduces the potential for failure. As I mentioned earlier, all batteries ‘self discharge’, and they’ll slowly lose their charge over time even if they’re not used; if a Lithium battery gets below 10% charge it may ‘lock up’ and will no longer hold a charge. My approach is this – once a year (usually New Year’s Day) I swap all of my active-use batteries with the ones I have in long-term storage. Using a smart charger, I discharge the active use batteries down to around 50% before storing them, then put the batteries that were in long-term storage into my active chargers to bring them up to full charge.
I have almost twice as many batteries in long-term storage as I do in active use, so I rotate them – the active ones get swapped for the first half in storage the first year, and those get swapped for the second half in long-term storage the next year. The result is that all of my batteries end up in long-term storage for two years. I know that this isn’t a perfect solution, but it’s a reasonable approach that doesn’t require me to individually measure every battery’s charge and swap them in and out of long-term storage on an ongoing basis. Every few years I start keeping an eye out for sales on rechargeable batteries and when I find a good deal I’ll buy some and swap them for the oldest ones, based the acquisition date I entered into my inventory system and the inventory tags on the batteries themselves.
While this approach works for most general purpose rechargeable batteries, some unique ones require a different approach. For example, the batteries for some of my drones tend to self-discharge a lot quicker, so I need to swap those out more frequently or else they get so low won’t take a charge (and they’re not cheap!). I set up separate reminder notifications in my personal calendar to remind me when to swap those.
Devices with built-in rechargeable batteries are another special case. These tend to be more expensive and since it’s difficult to open them up yourself and replace the battery I use a custom charging schedule for them as well. For the first year or so after I receive a new device I check its charge level regularly to get a feel for how fast it discharges, especially if I’m not using it frequently, and use that information to build custom recharge reminders. Many newer devices have very intelligent battery management systems built-in and can retain a significant charge even after sitting idle for a long time.
Note that even if the device isn’t designed to have its battery swapped you can sometimes locate details on what battery it uses and how to swap it at places like IfixIt [9] or YouTube. Make sure you save that information somewhere, as this allows you to buy a spare battery and keep it charged external to the device, and if the internal battery dies sometime after the Internet becomes unavailable you can swap it for a fresh one and keep using the device. Note that this will typically require the ability to open up devices that aren’t designed to be opened and do some basic analysis and repair – check out my previous article on repairing electronics [10].
Another scenario to consider is when you store removable batteries in devices so that they’re ready to go, such as a radio or flashlight in your bug-out bag. Many ‘smart’ devices consume a small trickle of power even if they’re not turned on, which can run your batteries down quicker and result in a dead battery that can’t be recharged. If you’re going to store removable batteries (primary or rechargeable) in a device that will remain unused for a long time I recommend making sure the batteries aren’t actually in contact in the device. I use a small piece of transparent tape folded in half between one of the batteries and it’s contact terminal in the device to break the connection. If I have to bug out and need the device I can simply remove the battery cover and pull out the piece of tape. Note that I include any rechargeable batteries stored in devices in my annual rotation schedule.
Summary
I realize that this article has included a lot of very technical information, but if you want to get the best possible use and longest lifetime out of your mobile electronics it’s critical that you understand and take care of the batteries that power them. Just buying a bunch of cheap no-name AA batteries at your local dollar store and tossing them in a drawer is not a viable long-term preparation; you need to start understanding what kinds of batteries you need, what devices you have and how you use them.
Begin by documenting what types of devices you have and what kinds of batteries they use, how often you need to recharge and how long they last in your devices, then start implementing a structured approach to battery management. Look for sales on things like rechargeable batteries, chargers, voltage meters, etc. and gradually start building up the kit that best fits you needs, but purchase quality batteries and chargers to reduce the risk of fires. Also, you should understand how to treat your batteries to minimize risk and have the appropriate gear to fight fires if they do start.